The resist system, consisting of a bottom layer of copolymer, germanium, and a top layer of PMMA, is exposed with an e-beam system. The top resist is developed and afterwards the pattern is transferred into the germanium layer by a dry etching process. To get a large undercut in the copolymer layer another dry etching process is necessary. This results in a free-standing germanium bridge (a).

Onto this resist mask, 4 evaporation steps under different angles are performed. With the first two evaporation steps of aluminium, a gap between two electrodes is produced (b, c). The tunnel barrier is generated by an in situ oxidation of the aluminium layer. During the third and forth evaporation step Au/Pd is evaporated (d, e). Due to the larger tilting angles, the gap is closed by an Au/Pd dot with twice the thickness of a single layer. In a final dry etching process, Au/Pd is thinned. During this step the Au/Pd dot in the centre of the electrodes was separated from the Au/Pd layer on the substrate (f, g). Samples have been produced using this method with island sizes < 30 nm in diameter.